This review provides an overview of the synthesis, reactivity, and applications of low-valent transition metalate anions, focusing on their roles in small molecule activation and catalysis. The article highlights the significant advancements in the field over the past 15 years, driven by improved synthetic methods and ligand design. Low-valent metalates, stabilized by various ligands such as carbonyls, isocyanides, alkenes, and phosphines, are highly reactive and have shown promise in catalytic processes involving hydrogen, nitrogen, carbon monoxide, and phosphorus. The review discusses the synthesis of these metalates, emphasizing the influence of ligands on their structure and reactivity. It also explores their applications in catalytic transformations, including hydrogenation, nitrogen activation, and carbon dioxide activation. The article covers various metalates, including those with carbonyl, isocyanide, and arene ligands, and discusses their reactivity toward small molecules. The review also addresses the role of ion-pairing and metal-metal bonding in stabilizing these metalates. Overall, the review aims to provide a comprehensive understanding of the chemistry of low-valent transition metalates and their potential in catalytic processes.This review provides an overview of the synthesis, reactivity, and applications of low-valent transition metalate anions, focusing on their roles in small molecule activation and catalysis. The article highlights the significant advancements in the field over the past 15 years, driven by improved synthetic methods and ligand design. Low-valent metalates, stabilized by various ligands such as carbonyls, isocyanides, alkenes, and phosphines, are highly reactive and have shown promise in catalytic processes involving hydrogen, nitrogen, carbon monoxide, and phosphorus. The review discusses the synthesis of these metalates, emphasizing the influence of ligands on their structure and reactivity. It also explores their applications in catalytic transformations, including hydrogenation, nitrogen activation, and carbon dioxide activation. The article covers various metalates, including those with carbonyl, isocyanide, and arene ligands, and discusses their reactivity toward small molecules. The review also addresses the role of ion-pairing and metal-metal bonding in stabilizing these metalates. Overall, the review aims to provide a comprehensive understanding of the chemistry of low-valent transition metalates and their potential in catalytic processes.